A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication.

Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions

Density functional theory calculations explain copper's unique ability to convert CO2 into hydrocarbons, which may open up (photo-)electrochemical routes to fuels.

How copper catalyzes the electroreduction of carbon dioxide into hydrocarbon fuels

Rising atmospheric levels of carbon dioxide and the depletion of fossil fuel reserves raise serious concerns about the ensuing effects on the global climate and future energy supply. Utilizing the abundant solar energy to convert CO2 into fuels such as methane or methanol could address both problems simultaneously as well as provide a convenient means of energy storage. In this Review, current approaches for the heterogeneous photocatalytic reduction of CO2 on TiO2 and other metal oxide, oxynitride, sulfide, and phosphide semiconductors are presented. Research in this field is focused primarily on the development of novel nanostructured photocatalytic materials and on the investigation of the mechanism of the process, from light absorption through charge separation and transport to CO2 reduction pathways. The measures used to quantify the efficiency of the process are also discussed in detail.

Photocatalytic reduction of CO2 on TiO2 and other semiconductors.

This paper reviews recent progress made in identifying electrocatalysts for carbon dioxide (CO2) reduction to produce low-carbon fuels, including CO, HCOOH/HCOO−, CH2O, CH4, H2C2O4/HC2O4−, C2H4, CH3OH, CH3CH2OH and others. The electrocatalysts are classified into several categories, including metals, metal alloys, metal oxides, metal complexes, polymers/clusters, enzymes and organic molecules. The catalyts' activity, product selectivity, Faradaic efficiency, catalytic stability and reduction mechanisms during CO2 electroreduction have received detailed treatment. In particular, we review the effects of electrode potential, solution–electrolyte type and composition, temperature, pressure, and other conditions on these catalyst properties. The challenges in achieving highly active and stable CO2 reduction electrocatalysts are analyzed, and several research directions for practical applications are proposed, with the aim of mitigating performance degradation, overcoming additional challenges, and facilitating research and development in this area.

A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels

We report new insights into the electrochemical reduction of CO2 on a metallic copper surface, enabled by the development of an experimental methodology with unprecedented sensitivity for the identification and quantification of CO2 electroreduction products. This involves a custom electrochemical cell designed to maximize product concentrations coupled to gas chromatography and nuclear magnetic resonance for the identification and quantification of gas and liquid products, respectively. We studied copper across a range of potentials and observed a total of 16 different CO2 reduction products, five of which are reported here for the first time, thus providing the most complete view of the reaction chemistry reported to date. Taking into account the chemical identities of the wide range of C1–C3 products generated and the potential-dependence of their turnover frequencies, mechanistic information is deduced. We discuss a scheme for the formation of multicarbon products involving enol-like surface intermediates as a possible pathway, accounting for the observed selectivity for eleven distinct C2+ oxygenated products including aldehydes, ketones, alcohols, and carboxylic acids.

New insights into the electrochemical reduction of carbon dioxide on metallic copper surfaces

A review of the aqueous electrochemical reduction of CO2 to hydrocarbons at copper

Electrochemical reduction of CO2 to hydrocarbons to store renewable electrical energy and upgrade biogas

Landslide Susceptibility Zonation through ratings derived from Artificial Neural Network

Bioavailability enhancement of curcumin by complexation with phosphatidyl choline.

We develop a technique to make on-demand routing protocols for ad hoc networks energy-aware. The goal is to increase the operational lifetime of an ad hoc network where nodes are operating on battery power alone. Our techniques uses a new routing cost metric which is a function of the remaining battery level in each node on a route and the number of neighbors of this node. The idea of the cost metric is to be able to route around the nodes that are running low in battery for which alternate routes are available. In addition, rerouting is done proactively when any node en route starts running low on battery while the route is being actively used. Further, we save energy by switching off the radio interfaces dynamically during the periods when the nodes are idle. Simulation results using AODV protcol show that combination of these techniques results in a significant improvement of the energy budget of the network as a whole resulting in increased operational life time.

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Nishant Gupta

Papers

A review of the aqueous electrochemical reduction of CO2 to hydrocarbons at copper

Electrochemical reduction of CO2 to hydrocarbons to store renewable electrical energy and upgrade biogas

Landslide Susceptibility Zonation through ratings derived from Artificial Neural Network

Bioavailability enhancement of curcumin by complexation with phosphatidyl choline.

Energy-Aware On-Demand Routing for Mobile Ad Hoc Networks